To my knowledge, there's no such mechanical interlock which would pull a throttle to IDLE should a reverser accidently deploy. The other side of such a "protection" is the accidental operation of such a system at an inappropriate time...the same logic (and thinking) which is being used in places to discuss an "accidental" deployment applies to all systems including one which is designed to retard a throttle to IDLE - in considering the design of such a system, would it be an actual mechanical link between reverser (which bucket?..top/bottom/both) to the throttles, (very difficult and not reliable), or sensor-driven (pressurization of the hydraulic cylinders which deploy either reverser)? While the problems aren't insurmountable, is the need there? Would the actuators within the pedestal or below the floor/pedestal be clutches (part of the MD80 autothrust system) or separate bell-cranks/cables? On the Airbus, FADEC simply commands IDLE, (not comparing types here, please) so should such a system be software-driven?
PJ2 being canadian you should know the CRJ system. It can break your thumb if you have it around the thrust lever
